Plasma apparatus

Abstract

The present invention relates to a plasma apparatus, in which a plasma is generated by the use of an electron cyclotron resonance, said plasma being introduced into a sample chamber where a sample is housed through a plasma outlet window by the use of a magnetic field for use in the electron cyclotron resonance, and said sample being subjected to a film-formation or an etching, characterized by that the distribution of magnetic flux density on a surface of the sample can be improved to uniform the plasma density, whereby subjecting the sample with the film-formation of uniformly thick or a uniform etching, by disposing a magnetic field forming means capable of forming a magnetic filed, wherein the magnetic flux density at the peripheral edge portion of the sample is higher than that at the central portion of the sample, on a side opposite to the plasma outlet window relatively to the sample.

What is claimed is: 
     
       1. A plasma apparatus, in which a plasma is generated within a plasma chamber by the use of an electron cyclotron resonance and the generated plasma is introduced into a sample chamber provided with a sample stage for placing a sample thereon through a plasma outlet window by the use of a magnetic field formed by an exciting coil disposed around said plasma chamber, comprising two electromagnets each having a cylindrical or columnar core with diameters different from each other and a coil wound around each core, said electromagnets being disposed concentrically with said exciting coil on a side opposite to the plasma outlet window relative to the sample on said sample stage for forming magnetic fields, the direction of the magnetic field generated by one of said electromagnets being the same as that of said exciting coil and the direction of the magnetic field generated by the other of said electromagnets being opposite to that of said exciting coil. 
     
     
       2. A plasma apparatus as set forth in claim 1, in which one of said electromagnets comprises a disc-shaped yoke provided with a columnar yoke at a center of one surface thereof and a cylindrical core, and a coil wound around said cylindrical core, said cylindrical core being disposed concentrically with said yokes and having a diameter smaller than a diameter of the disc shape yoke, and in which the other of said electromagnets comprises a cylindrical core having an inside diameter larger than an outside diameter of the one electromagnet. 
     
     
       3. A plasma apparatus as set forth in claim 1, in which the one electromagnet comprises a substantially columnar core thicker at the central portion than at a peripheral portion thereof and in which said other electromagnet comprises a cylindrical core having an inside diameter larger than a diameter of said columnar core. 
     
     
       4. A plasma apparatus, in which a plasma is generated within a plasma chamber by the use of an electron cyclotron resonance and the generated plasma is introduced into a sample chamber provided with a sample stage for placing a sample thereon through a plasma outlet window by the use of a magnetic field formed by an exciting coil disposed around said plasma chamber, comprising an electromagnet having a cylindrical core and two coils each wound inside and outside of said core, said electromagnet being disposed concentrically with said exciting coil on a side opposite to the plasma outlet window relative to the sample on said sample stage for forming magnetic fields, the magnetic field direction generated by one coil being same as that of said exciting coil and the magnetic field direction generated by the other coil being opposite to that of said exciting coil. 
     
     
       5. A plasma apparatus as set forth in claim 4, in which said core is provided with a sponson portion projecting inwardly and outwardly at an end portion of said core on a side opposite to the sample. 
     
     
       6. A plasma apparatus as set forth in claim 4, in which an outside diameter of said core is nearly equal to a diameter of said sample stage. 
     
     
       7. A plasma apparatus as set forth in claim 4, in which the core diameter of the portion on a side opposite to the sample is shorter than that of said the other portion and this shorter-diameter portion is surrounded by the coils. 
     
     
       8. A plasma apparatus as set forth in claim 4, in which the core diameter of the portion on a side opposite to the sample is larger than that of the other portion and this larger-diameter portion is surrounded by the coils.